ImageMagick

Do you need consulting from ImageMagick experts and are willing to pay for their expertise? Or are you well versed in ImageMagick and offer paid consulting? If so, post here otherwise post elsewhere for free assistance.

You might try my histmatch script? See the link below. I might be able to adapt it to use a mask of the skin tone areas, if you can create such a mask. The other possibility is to make a 1D image of all the unique skin tone colors and use -remap. This may need to be masked as well. See http://www.imagemagick.org/Usage/quantize/#remap